/Engine/Source/Runtime/Landscape/Classes/LandscapeProxy.h
Update the material instances for all the landscape components
void UpdateAllComponentMaterialInstances ( [FMaterialUpdateContext](API\Runtime\Engine\FMaterialUpdateContext) & InOutMaterialContext, [TArray](API\Runtime\Core\Containers\TArray)< class [FComponentRecreateRenderStateContext](API\Runtime\Engine\FComponentRecreateRenderStateCon-) > & InOutRecreateRenderStateContext, bool bInInvalidateCombinationMaterials )